


Detective Bones

by UndertaleTrashBin



Series: Mini Skelebros Aboveground [3]
Category: Undertale (Video Game)
Genre: Alternate Universe, Angst, Childhood Trauma, Gen, Kidnapping, Torture, lotsa angst
Language: English
Status: In-Progress
Published: 2016-06-12
Updated: 2017-01-16
Packaged: 2018-07-14 16:22:29
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 3
Words: 8,175
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7179950
Author URL: https://archiveofourown.org/users/UndertaleTrashBin/pseuds/UndertaleTrashBin
Summary: <blockquote class="userstuff">
              <p>The boys are adjusting to living with Undyne and Alphys on the surface, but it certainly isn't easy. Sometimes it's a blessing and a curse to have such competent and strong protectors, especially when it comes to painting a target on your backs by being Captain of the Royal Guard.</p>
            </blockquote>





	1. This Smells Fishy (or rather, lacks a certain fish mom)

**Author's Note:**

> So I had a hard time writing this? Idk why it was so difficult. I'm in a bit of a writing ditch as far as The King's Pupil goes and this fic seems like a lotta fun but there's some build up 'til we get to the interesting stuff. Stick with me pals! We'll get there ;)

Adjusting to the surface had been hard on the boys these last few months, but adjusting to authority and looking out for more than just each other was even harder for the skeletons. Papyrus seemed to be taking to it much easier than Sans, but then again, he’d had a much closer relationship with Undyne and Alphys to begin with.

The younger brother had actually started calling them his moms, but Sans had avoided the word. After all, they may be his bosses but they didn’t share their souls to make him. Nonetheless, the lack or the addition of the word didn’t seem to bother the couple and their cute little family unit had begun to rely on one another and truly see each other as family.

 

Sans grumbled to himself when Papyrus’s alarm blared in the early hours of the morning. It was part of his daily routine, waking up to turn off his brother’s alarm because the other was more than likely already awake. In fact, he was pretty sure the eight year old only left it there for Sans’s benefit and not in the event that Papyrus slept in. He abandoned his vividly blue race car bed and shuffled over to carefully turn the alarm off.

His brother’s bed was immaculate, the stark red of the car clashed slightly with the light, baby blue sheets. At least they were neatly tucked in, unlike Sans’s own red ones that stayed defiantly unmade at every hour of the day. Sans yawned and stretched, popping his back. A lovely smell wafted through the open doorway: the promise of an Alphys-made breakfast. Despite Undyne’s best efforts, she still had a long way to go before her food was pleasant, so Alphys was typically the one who made the food. There were, of course, spaghetti dinners after Papyrus’s “training nights” and to say the least, Sans had gotten quite good at turning off his taste buds and giving his best grin.

The small skeleton flipped on the lamp beside his bed and walked over to his closet. It wasn’t necessarily filled, but it had more clothes than he’d ever owned before. Papyrus had once again reorganized it for him, so it took a moment of searching to find the perfect pun shirt for the day. It was a school day, so he chose a pie based pun related to math. Toriel had gifted him it not too long ago now, and he knew she would appreciate seeing him in it in class.

Sans frowned when he realized all of his trusty basketball shorts were dirty, instead having to fish out a pair of jeans. It was early spring, so they wouldn’t be uncomfortable weather wise, but Sans was a kid all about comfort. Jeans were a bit on the formal side for him. He changed quickly and walked toward the stairs, but not before stopping outside of Alph and Undyne’s room. There was no sign of Undyne’s usual bustling about, the woman always woke up late without fail.

“undyne? boss?” He peeked his head in and looked around, but there wasn’t even a light on to indicate she was getting ready. With a short frown, he shrugged and made his way down the stairs. Paps’s voice echoed throughout the house, eagerly chatting to Alphys about what was going to happen at school that day and anything else that came to mind. But once again, there was no evidence that Undyne was home. Sans shuffled into the kitchen and plopped down at the table in his spot.

“hey alph, did undyne leave early today?”

“O-oh, good morning to you too Sans!” Alphys jumped a bit, then bopped the ten year old on the head affectionately for scaring her. He chuckled but waited for an answer to his question. “N-no, I’m not exactly sure where s-she is. She had to go into the human’s side of the city yesterday, b-but hasn’t been back.” The woman frowned, and Sans’s expression darkened. Monsters went missing in the human city all the time, only for dust their to be retrieved later. This wasn’t exactly a simple issue.

“is she ok? are they looking for her?”

“Yes Sans, o-of course they are! The guard’s been on it all n-night, I’m sure she’s fine.” She sounded like she was reassuring herself more than Sans when she spoke, and Papyrus looked deep in thought. Sans raised a brow bone at his brother, who gave him a grin and a nod in response. The two had nearly learned a nonverbal language with how they could talk through looks. This meant for Sans to drop the issue for now, they’d chat later.

“... sooo, what’s for breakfast?” Alphys shook her head with a somewhat strained laugh, appreciating the change in topics Sans sent her way.

“Toast and eggs. I swear, w-with how much you eat w-where does it go?” She piled eggs onto three plates and dropped buttered pieces of toast next to it before setting the plates down in front of the boys and in her own place at the table.

“was that a short joke?” Sans feigned offense. “from you, al? of all people?” Alphys rolled her eyes.

“You’re s-still shorter than me Sans.”

“NYEH HEHE! Owned!” Papyrus giggled at the grumpy expression Sans shot him. The younger brother had grown several inches since they’d begun living here and was approaching Alphys’s height quickly. Sans on the other hand, had not grown a single inch.

“you’ve been hanging out with undyne too much.” He grumbled into his food, not really offended or upset by the teasing at all. The three of them finished up breakfast quickly and split up to gather their belongings for the day. Alphys mainly because she worked as a mechanical engineer now, she had become quite adept at integrating monster magic into human technology to increase efficiency of different products. Currently, she was working with cars to see if magic could be used as an alternate form of fuel.

Sans popped on his faded blue jacket with a fur lined hood. The weather was below freezing again today, so he also grabbed a pair of gloves. Papyrus never seemed to take his gloves off so he already had the vibrant red pair on, but he adjusted his scarf into a puffy orange coat. The kid looked ready to roll around in snow, and it made Sans laugh a bit. They each grabbed their backpacks and hugged Alphys.

“H-have a good day, boys.” She kissed both of them on the head, much to Sans’s surprise. He looked... Embarrassed? Flustered? Either way it was cute as he ran out of the house, Papyrus on his heels. Alphys giggled as she watched them run off until they were out of sight. Her thoughts fell back to Undyne, and worry pulled at her soul. Something wasn’t right.

The boys made their way toward the school, both in deep thought. The walk wasn’t that long at all, but they always left a little early to have time to dawdle and take everything in. Eventually, Papyrus broke the silence.

“Sans?”

“yeah, bro?”

“Do you think Mom needs help?”

“mm, i’m sure boss is fine. the guard will probably find her and she’ll be at home waiting for us when we get back.” It was an empty reassurance and they both knew it, but they held onto the hope that Undyne was too important and strong to just be murdered or kidnapped too easily. This  _ was _ the leader of the royal guard they were talking about, after all.

________________________________

 

School went by quickly, it helped that both of the skeleton brothers were in the same class and enjoyed it thoroughly. Frisk and Monster Kid (known simply as MK to most everybody) also shared the classroom, and their teacher was Toriel. Sans had gotten a chuckle from her when he walked in that morning, which was enough to put the grin on his face. Papyrus was not nearly so impressed, rolling his eyes at the pun war that ensued and contained his groans with great restraint. He often wondered who was punishing him by putting him in this class. (Then Sans would laugh and say “ _ pun _ ishment, you say?”. It would finally prompt a frustrated screech of anger, and though he would act upset, Papyrus could be seen smiling underneath his anger.)

When the day finally came to an end the boys gave their goodbyes and began the trek back home. It was easy to block out their worries for their caretaker during the day, but now that they were heading home it hit them full force. Would the monster be back waiting for them? If she was, would she be alright? Would Alphys be there? What if they had gone off to a healer and they were home alone? Papyrus began to pick up the pace.

“... do you just want to teleport home today, bro?” Usually their walks were the only time they had to themselves that wasn’t supervised, it was typically the time they could gossip a bit or discuss things that happened. Today it was a barrier of suspense.

“Yeah, let’s do that.” Papyrus snagged his brother’s hand, gripping it tightly. It had been a while since Sans had teleported. There were times that he offered it to Undyne and Alphys, like trips to the store or other little things, but they always seemed hesitant or said something about smelling flowers. Sans teleported them just outside the house, but was startled to find the driveway was full of vehicles. All of them were marked for the Royal Guard but resembled police cruisers. Undyne had one just like it, though the boys hadn’t been particularly excited to ride in a police car again. The last time hadn’t exactly been pleasant.

Sans and Papyrus exchanged a look before walking through the cars to the door. There was a quiet murmur from the other side, too soft for them to decipher. He felt bad about interrupting something potentially so important, but Sans opened the door anyway. The talking immediately came to a stop, and the brothers peeked around the door. The entire canine unit of the guard greeted their eye sockets, and while Sans would normally be overjoyed to see the odd sort of friends he’d made at Grillby’s, it only made him worry more. Undyne was lost or dead, then. It didn’t help that Alphys’s eyes looked red and watery, she had clearly been crying. Still recovering and nervously, she smiled at the boys, already poised to apologize. Dogs and bones weren’t known for mixing well. Before she could say anything, the dogs spoke up, relieved to have a distraction.

“My nose smells little bone pups!” Dogaressa exclaimed happily, a wide grin replacing the sad expression previously on her face, Dogamy chuckled at them too.

“Don’t tell me that movement was Sans and Papyrus?” Doggo’s head was turned towards them, and Sans waved to help the monster see him. Alphys looked startled but relieved.

“O-oh? You kn-know them?” Had the boys gotten into trouble or something? Wouldn’t Undyne have been informed about that? The dogs exchanged an amused look and started laughing.

“Know them! Sans was a regular at Grillby’s back in ol’ Snowdin.” Dogamy grinned. “And Papyrus was the best little sentry in training known to the underground.” Pride washed over Papyrus’s face and he grinned broadly, bringing his hands to his hips as they walked over. Dogaressa giggled and patted Sans on the head as she stood. He smiled up at her.

“Don’t go telling me the skeleton brothers are the captain’s new pups?! I’d heard she had gotten little ones, but these two?” Sans winced at the unasked question of who watched out for them before they got the surface, but the dogs didn’t seemed to pry.

“Don’t tell me you were spyin’ on us for her, were you?” There was a teasing sort of betrayal in Dogamy’s voice. Sans grinned and shook his head.

“one slacker to another guys, i would never.” He spoke calmly, knowing it would annoy Pap.

“SANS! HOW OFTEN WERE YOU AT GRILLBY’S?!” Papyrus shook his head at his brother, throwing up his hands and stomping his still booted foot. It wasn’t the first time Sans had been lectured in front of the dogs and he winked at them before shrugging. The entire room seemed to have lightened up since they walked in, but both boys were insanely curious about what actually had been discussed. Instead, all the dogs began to leave. The boys got several pats and even a couple friendly licks- much to Papyrus’s disgust at the germs- on their way out.

“Bye, pups!”

“See ya’ at Grillby’s kiddo!”

The skeleton brothers turned back to Alphys expectantly, but she had already turned away and was heading towards the kitchen. They followed at her heels.

“Boys!” She called out, expecting them to have stayed in the living room.

“yea?” Sans responded directly behind her, making her jump. She gave him a very unimpressed look when she turned, Papyrus giggled at his misfortune.

“D-don’t do that!” After a deep breath she continued. “What sounds good f-for dinner?” Papyrus frowns sharply.

“It’s tuesday! Spaghetti night!” Alphys’s expression fell too though she immediately tried to correct it.

“Sorry Pap, t-training’s postponed until Undyne g-gets back. How about that new pie recipe T-Tori sent me?” Sans was about to shrug when the doorbell rang. Everyone froze for a long, tense moment. Eventually Alphys skittered off towards the door. The younger brother dutifully sat at the table and ignored it, but Sans silently slipped by and to a place he could over hear who was at the door. He’d be damned if Alphys were harmed while Undyne wasn’t here to protect her. The door creaked open, audibly stopped by the chain lock.

“Hello? H-how may I help you?”

“Is this the monster captain’s residence?” Sans peaked around the corner stifling his own gasp. There was a human outside, a human policeman. He thought vaguely recognized the man. His hat was under his arm, his face looked solemn.

“Yes!” Alphys squeaked, not caring at the slip up of composure. “Have there been any d-developments on the human front?” Sans briefly wondered what that meant. Could the humans be doing something different than the guard...?

“Yes, ma’am. The cameras have confirmed the captain was attacked on her way home, but not dusted. It is the current belief that she’s being held hostage, our men are looking for leads.” Sans can hear Alphys’s claws tighten and make the wooden door creak under the pressure.  _ cameras, maybe they have better access to technology? that makes sense. the dogs can only get so far with their noses. _

“What groups would b-be targeting her? Why is-” Alphys’s voice speeds up to rush the questions out, she clearly has a million on her mind and they were no doubt crucial ones to finding Undyne. Sans was curious as well, but the policeman’s expression held no room for argument, and he raised a hand to stop her.

“That’s classified for now. I'm sorry we don’t have more information, but there isn’t much that can be revealed. They’re doing all they can.” There was an annoyed impatience to the man’s voice, and Alphys met it with a frustrated growl.

“You m-mean the  _ monster _ unit it doing all they can.” The implication the humans didn’t really care didn’t seem to strike the human at all. In fact, the man seemed incredibly casual about this situation altogether. Sans wasn’t sure if this caught Alphys’s attention or not, but he narrowed his eyes, trying to read the man’s expression. Was he trying to emotionally separate himself from this or did he really not care? Ugh, humans were to hard to read.

“That’s what I said. Good day.” The policeman stalked off and Alphys slammed the door in an almost Undyne-like fashion. Sans was processing this information with intrigue. He hadn’t been aware there was a specific group of policeman set aside to deal with monsters, but now that they mentioned it it made sense. But was it balanced? How big was the monster unit? Did they have the same equipment and capabilities of other policemen? Sans suspected not by Alphys’s frustration.

Before Alphys could make it back the the kitchen he teleported into his chair, falling with a little huff. He expected her to be in quickly, but it was taking a while. Worry must have begin to show on his face as well because Papyrus began to get antsy sitting in his chair. Just as Sans made a move to get to find her, she dragged herself into the kitchen. Her face wasn’t turned to them, but there was an audible sniffle and a hand wiping under her glasses. Both boys stood and watched in a frantic worried state before exchanging another long look. What could they do to make this better? They felt so helpless. Then, just as soon as she had seemed to have finally broken down and cried, she shot the boys a small smile and turned to get stuff out from the fridge. They both let out breaths they didn’t know they were holding. It was so disconcerting to see Alphys this way... And that was in front of them. Who knew how she was faring behind closed doors? Now that Alphys was bustling about the kitchen quietly, Papyrus stared at Sans expectantly. He shook his head once before gesturing to the stairs and jerking a thumb up them. The boy deflated in response, but nodded anyway, he got the idea.

“Uhm, hey... Mom! Sans and I are gonna go upstairs and play, is- uh... is that ok?” His eyes stared at her, wide and concerned. It seemed like the monster might like some time to herself, but he didn’t want to assume. Alphys looked to them and after a brief moment of suspicion, shrugged. It was rare that Sans asked permission to do anything, but the boy seemed to watch her for confirmation too.

“A-alright, but be ready for dinner. It sh-shouldn’t take all that long.” Her voice was even shakier and stuttered than usual, but the confirmation was all they needed to rush up the stairs. It made the still heartbroken monster laugh, just a little. She hoped they weren’t all that aware of the situation, but it was fairly obvious that Sans was too attentive to not have noticed. Sometimes ignorance is a blessing. She huffed and turned back to make dinner, but not before flipping on one of her favorite anime OSTs.

After crawling into the safety of their room, the boys took their seats on the brightly colored MTT themed rug to talk. Sans immediately tossed off his socks upon entering the room, and Papyrus shot a nasty glare at the rising pile of dirty socks.

“So what did you hear?” The younger got straight to the point, Sans couldn’t help feeling a little like a spy at the wordless understanding he had eavesdropped. In any other situation he might have been proud of that.

“it was a human cop.” He responded grimly, picking at the carpet beneath them. Papyrus gasped, leaning in intently. “talkin’ about boss. she’s been taken by someone, they dunno who yet.”

“Well, what the heck!” The younger boy shouted out in anger, quickly throwing his hands over his mouth and wincing. “I’m sorry Sans, I don’t mean to curse! But it’s been like a whole day or two! Are they even trying?” The question made his grin twitch, remembering the human’s passive attitude. Was it an act? He couldn’t safely say it was.

“they said the whole monster unit was on it, but alph didn’t seem happy about that answer. so probably not as hard as they need to be.” He grit his teeth and glared at the fibers of the rug, picking at it with more vigor. There were so many things that could be happening to their caretaker, and everything his mind provided struck fear and concern in his soul, even though they were vague and uninformed possibilities. Papyrus didn’t seem to be much better, and, with a huff, he stood suddenly, running over to his backpack and pulling something out. Sans cocked his head to the side as he watched.

“whatcha got there, bro?”

“A map! If the humans aren’t going to find Mom, we’ll just have to.” There was an all too familiar look of determination on the boy’s face that made Sans’s stomach drop. This was not going to be remotely safe for his little bro to be involved in. In fact, Sans had already decided he was going to look for the woman, just not alongside Papyrus. And yet, that was the look the younger wore when Sans said Pap wouldn’t have to work and that he would bring in the money, or when he offered the drier side of the box to the little guy while sitting in the rain. It brokered no arguments, so he wouldn’t even bother arguing.

“... fine. but if we’re gonna do this, we’re gonna do it together. no running off alone without saying anything, no being the hero.” He replied with a huff. Sans gave his brother a pointed look that Papyrus only nodded at. He searched the boy’s eye sockets for a moment, looking for a hint of disagreement. When Sans found none, he nodded, the deal was settled then. “then tomorrow we’ll start looking.”

“We have school tomorrow!” Papyrus cried out, offended.

“so?”

“So! So! We’ll get in trouble...”

“nah, not if we find her.” Sans shot him a reassuring grin, but there was still an uneasiness to Papyrus’s expression. “when else are we supposed to look?” Reluctantly, Papyrus nodded.

“Alright. Tomorrow.”

A nervous sounding Alphys called them down for dinner and they exchanged a final look before heading down.


	2. Back To Our Roots

**Summary for the Chapter:**

> Skippin school is not cool kids.

**Notes for the Chapter:**

> First of all. I'm sorry this took so long. Camp + Writer's block murdered me.  
> Second. I'm not super happy with this chapter. I'm very excited about things to come, but for now i'm doin my best.
> 
> thanks to my beta belzarvie.tumblr.com

The next morning Sans was up before Papyrus. It was so rare that Papyrus was startled to wake up to their room softly lit with his brother’s lamp on. Sans was sat on the floor, going over the map he’d laid out the night before. Their backpacks sitting next to the foot of his bed, the school supplies the packs usually held were laid out across the floor. He wondered what now filled them, they didn’t look empty at all. One of Sans’s pens was in his hand, being twirled around his stubby fingers slowly as he stared at the map with an intense concentration.

“Brother?” Papyrus asked softly. He giggled when Sans looked up at him sharply, startled. It was hard to catch Sans in a place he could be surprised, the boy seemed prepared even in his sleep. Sans’s expression relaxed into an easy grin and he rubbed the sleep out of his eyes.

“mornin’ lazybones.” The lazy grin gained a bit of mischief and Papyrus positively pouted.

“Did you stay up all night?” He chastised with slight annoyance. With Sans he either got a full night and some or he didn’t sleep at all. Papyrus was certain the sleeping schedule would come back to bite his brother someday, but for now it seemed to work for him. Unfortunately.

“psh.” Sans made the sound, more confirming than denying, and stood, popping his back as he stretched out.

“EW! Sans!” The younger brother’s face looked horrified. He was firmly of the belief that their bones weren’t meant to make such sounds. Sans disagreed, clearly, as he continued to pop his neck just to vex him. When Sans just shot him an amused look with a raised brow, Papyrus shook his head and slipped off his bed to look at the map alongside his brother. A few areas had been marked, albeit lightly, it was clear the strokes were made to not obscure to view of the map itself. Sans had been careful; good! “Where are we starting?”

“the border.” Sans walked to the closet and Papyrus could hear the hangers clacking together as he shuffled through it.

“Where, though?” He asked, watching with growing interest. The elder hummed in response, tossing a few articles of clothing on the bed. They landed with a heavy thump, he was clearly grabbing thicker knit stuff. The snow outside alone would be fine on the skeletons, but the breeze was biting when it went right through you.

“ ‘round the shopping district first, i’m thinkin’.” It was like a lightbulb went off in Papyrus’s head and he turned to stare at Sans.

“Where we used to live?”

“if you want to put it that way, yeah. what, you wanna visit the ol’ box?” There was a conflicted look on Papyrus’s face before he shrugged.

“Why not? Maybe at the end of the day, though...” No need to ruin the entire experience with old memories. Sans nodded in agreement and moved to Papyrus’s closet. “What are you doing?” Papyrus snickered before standing to search alongside Sans. The older huffed indignantly and pulled out a thickly knit sweater and jeans. It matched the outfit he’d laid out for himself, the sweaters had been handknit by Toriel and were Christmas presents. Papyrus’s had elegant lettering that led into the beautiful pattern saying “Cool Dude” and Sans’s had a bone pattern with “Lazybones” stitched in. Frisk had one that matched them too, but it had a little red heart instead of a cool nickname.

“need somethin’ warm to wear, bro! the cold will go-”

“Sans, don’t.”

“the cold will go ri-”

“Sans.”

“it’ll go right thr-”

“I’ll disown you.”

“i’d like to see you try.” Sans grinned brightly at him, and Papyrus made an annoyed huff before taking the clothes under his arm. “the cold’ll go right through you!”

“SANS!!!” A pillow was thrown at his head, but he dodged it easily, grinning and bringing his hands out of his pockets to give an exaggerated shrug.

“eh, don’t dis-bone me yet, bro. you  _ sweater _ believe i can go all da-” He dodged another pillow, thinking it was over before a pillow from his own bed clocked him from behind. Sans snorted out a few giggles and stared at Papyrus in surprise. The younger brother grinned back, looking proud.

“SHUSH! We have to be ready, your jokes aren’t helping.”

“aren’t they, though?” Sans didn’t wait for a response before changing into his warm clothes. It was almost stifling to wear them inside, but he knew they would appreciate the extra layers later. Who knew if they’d be able to get inside until they came home today? After dressing, he returned to the backpacks he repacked overnight. Snacks, a bit of their allowances, band-aids, and other assorted items rested inside. He may have overpacked Papyrus a little, but he wanted to make sure the boy had plenty of stuff keep going if they got separated. That, and he planned on keeping the map with him; he needed room for that still.

“We should probably say good bye to Mom before we go.” Papyrus said, crouching down in front of his own bag as Sans rolled up the map.

“yeah, she’s worried enough...” Sans sighed, finishing packing up and tossing the backpack on his shoulders. He felt bad, she’d freak when Tori called from school. Maybe he could text Frisk that they wouldn’t be in? They’d understand, if not see right through them. “she’s probably still in bed.” He remarked, shooting a text to Frisk and turning off their shared phone before tucking it into the pocket of his jeans.

“Sans... Maybe we shouldn’t...” Papyrus looked uncomfortable, and spoke unusually quietly. The thought of Alphys freaking out that they might have been kidnapped or killed too was heart breaking.

“aw, don’t worry, paps, we’ll be back here ‘round the usual time. in and out!” He snapped his fingers, putting on a grin more confident than he felt. Sans was assuring himself as much as he was Papyrus. With a deep breath, he stood, holding a hand out for his brother. Papyrus nodded after a moment and took the hand, swinging the bag over his shoulder and standing in one motion.

“Okay! Let’s go find our Captain.” There was his brother’s confident, determined smile. It made Sans grin brighter in turn. Hand in hand, they walked out of the room.

It became apparent as they walked down the hall that Al wasn’t awake. It was so disconcerting to have the house so quiet, even when it was the dead of night and everyone’s asleep, Sans or Undyne’s snoring echoed through the halls. It choked Papyrus up a bit, they needed to find her, fast. Sans stopped in front of their parents’ room, peeking in. Alphys was dead asleep on the bed. The two walked in quietly.

“MOM!” Papyrus said, jerking the poor monster awake.

“WHAT?!” Alphys yelled in return, looking around rapidly before settling on the two boys and holding a hand over her pounding heart. “Good lo-lord... You tw-two scare-ed the fu... the cr-crap out of me.” She corrected herself mid sentence, but Sans already snorted knowingly. The bar goers didn’t always keep their mouths clean just because he was present.

“We’re heading to school!!” He spoke confidently, the lie flew out evenly and without even the slightest stutter. His expression was just as trained, and Sans stared at him in surprise. Was Papyrus always this good at lying?

“What...? I’m not late, am I?!” Alphys turned quickly, fearfully, searching for the time displayed on the digital clock by the bed.

“nah, we’re just helping tori set up an experiment for today.” Sans spoke, just as evenly, rocking on his feet. His nerves came across as excitement.

“It’s very elaborate!” Papyrus agreed, nodding.

“Oh.” Alphys said, once again looking back to them with relief. “A-alright, be ca-careful.” She rested a hand on Papyrus’s head, pecking him on the forehead before moving to do the same to Sans. “I think w-we have so-some protein bars, grab something for br-breakfast. Be good...” Her voice trailed off as she rolled over, already back asleep.

“Bye!”

“later.” The boys each bid their farewells for the day, creeping out of the room quietly. Papyrus gave the monster one final look before leaving, his soul in his throat with guilt.

Sans lead the way down the stairs, stopping at the bottom to slide on his snow boots. They matched Papyrus’s, lighting up blue when he stomped. He felt a little old for them, but if they were cool enough for The Great Papyrus, they were sure as heck good enough for him. Papyrus made his way to the kitchen first, returning to Sans and handing him one of the protein bars Alphys had told them to eat. The older brother took it without complaint, the two finished getting their coats and boots on as they munched on their bars. It took longer than it usually did, Papyrus had gotten tangled in the sleeves of his coat and had to take it off and completely restart, but they eventually succeeded and were out the door. Papyrus was sure to lock it behind them, but each boy was unusually tense as they began their walk- in the opposite direction than usual.

The two didn’t talk much, each deep in thought as they made their way through the empty morning streets. The cars that passed grew more steady as the morning moved on and the sun rose higher in the sky. Monsters, strangers passed them on the street, rushing to their jobs or to grab daily groceries. The boys received a few judging looks, several amused grins, and a lot of knowing head shakes. Luckily, they didn’t come across anyone willing to question exactly why the boys were not in school and without their parents. Papyrus seemed mostly oblivious to the attention around them, but Sans shrunk under the many gazes. Did they gather this much attention when they were alone? He didn’t think so, he would have noticed. Then again, the shopping district was far more crowded than the town of Snowdin or the winding halls of Waterfall. It was more like living in the Capital.

“So, just checking the alleys?” Papyrus asked, nearly skipping as the two made their way down the city sidewalk. Sans nodded, pulled out of his concerns.

“yeah, checking the places adults always seem to forget.” Sans thought back to his map, keeping up with Papyrus’s eager and antsy pace. “There are a few buildings on this side of the border no one lives in, but if humans got her- ‘cause i doubt monsters are behind this- she’s probably on the other side.”

“Well! We can check over there too, now!” The border had been opened up a while ago, but it was dangerous for monsters to even be near it, better yet two monster kids traveling alone on the human side... It was like asking to be mugged or lynched.

“ehh, if it comes down to it...” Sans’s apprehension showed on his face. “probably not today though.

As the border grew closer, shops fell off, leaving an uneasily barren area with plenty of shattered glass and trash littering the streets. It was familiar, but strikingly different. These streets used to be clean and practically untouched, only Papyrus and Sans seemed to transverse them. Now they sent a shudder of fear down the older’s spine. Something was off. Still, in the brightness of the morning they found themselves alone.

The first few alleys were just as they remembered, an occasional bit of trapped trash, but ultimately lonely and uninhabited. It took hours of not just looking for external signs of struggles but also magical signatures. There was way more magic used in the area than Sans would have expected, but none of it was Undyne’s or anyone they knew’s. By the time they made it to their old box- the thing had lasted through the winter by freezing stiffly in place- it was time for lunch.

Sans sat and Papyrus dropped his bag, rifling through for the food Sans had packed him. Little snack packs, cookies, and apples. Nothing that was a solid meal, but Sans had always been a snacking kid.

“Here!” Papyrus said, handing his brother an apple.

“thanks, but i packed stuff for me too, bro.” Sans shrugged his own bag off his shoulders and pulled out a bottle of ketchup from home for emphasis. The younger brother’s face scrunched up in disbelief.

“Gross. Eat real food too, Sans!” With that, Papyrus took a big bite of the previously offered apple, munching happily.

“eh, when i get hungry.” He laid back in the box, right where he used to sleep. His body was a bit too long for it now, but Papyrus was even worse! The kid barely fit inside with both of them there now. They fell into a comfortable silence again, eating or drinking their lunches respectfully.

“Do you think Mom would have taken us in if we were still underground?” Papyrus asked, almost randomly. His fingers rolled a bit of cardboard between them. The circumstances around their adoption were a little tricky. Sans took several moments to answer, thinking the question over.

“i think undyne would have taken us in from the start if she had known.” He responded honestly. The younger turned to look at him, brows knitted in confusion.

“Why didn’t we ask?”

“i’m not sure... just, felt wrong. rude?” Sans questioned, taking another sip. “weird.”

“I don’t think she would have found it weird.” Papyrus stated, thoughtfully. “If anything, she’d just find somewhere else for us to go! Right?”

“maybe. i didn’t want to risk being separated, though.” Sans sighed. “besides! it worked out better this way. well, if we can find her again-” The sound of a large body hitting the brick wall further down the alleyway made Sans stop short. The two exchanged worried looks.

“What was-” Papyrus began, only to be cut off by Sans putting a hand over his mouth and motioning for him to be quiet. They sat there tensely, waiting for something else to happen. After a few moments of heavy breathing echoing through the alley, a bold and  _ angry _ voice spoke.

“We need more!!! The deal was ten by the end of the week, you brought us  _ six _ .” A voice growled out angrily. Papyrus’s eyes widened and his breath hitched, Sans remained very still, trying to listen.

“I just need more time! Look, I’m on this side of the border for a reason-” The voice of the pleading man was cut off by a gunshot, and it made both boys jump in shock. It was a common sound from a distance, but much,  _ much _ louder so close by. Papyrus whimpered under Sans’s hand, and the older brother made quiet shushing sounds. They needed to get out of here, fast.

“You’ve had time. Our cover can only last so long, monsters are going to start taking action on their own.” Another, quieter thud against the wall sounded, followed by the strangled beginning of a sentence. “No, shut up. Here’s what you’re going to do. We need four more by tonight- Did that box just move?” The menacing tone dropped mid sentence, into one of surprise. Inside their old makeshift shelter, both boys tensed in fear. Don’t... move. After a few silent, tense seconds, Sans leaned forward slowly

“grab your stuff, quickly.” Sans whispered almost silently, pulling away to stuff what he’d gotten out into his bag. His hands were shaking, trying to make as little motion and sound as possible.

“Oh yeah, it definitely moved that time.” The wet crunching of footsteps in the sludgy, snowy alleyway marked the person growing closer. The sound timed the boys, filling their souls with anxiety and urgency as the sped to fill their bags. Sans grabbed his brother’s hand, just as a very  _ human _ hand reached down and pulled their makeshift roof back. He pulled Papyrus close, but he wasn’t quite fast enough. His eyes caught the human’s face, the man caught the small skeleton’s in return, and panic overrode Sans’s focus on where he was teleporting out to. The magic filled the air, and the two disappeared, leaving the box empty.

The void space was a temporary relief, Sans randomly pinpointed somewhere in the city to land. There was no time to relax, though, sound flooded their ears. Screams sounded, Sans felt someone hit against his back and head hard. He held Papyrus close, pressing his brother’s head down as he finally lifted his head to look around. They were surrounded by humans, most of which looked terrified.The second seemed to pass, and people began walking past them, urgently. A hand gripped his arm, pulling him to his feet. Sans winced, preparing to be hit and pulling Pap up with him.

“Well! If that ain’t a familiar little skull!” The man patted his head- the familiar man. Sans turned, relaxing at the sight of the blue uniform and friendly face.

“dupoir?” He asked after a moment, Papyrus clinging to him from behind.

**Notes for the Chapter:**

> HAHAA cliffhanger *finger guns*


	3. The Police

**Summary for the Chapter:**

> Sans and Papyrus are at the police station. They, per usual, are quite the pains in the ass.

**Notes for the Chapter:**

> Welp I'm sorry this is so late and so short. But! I'm going to work on the next chapter today, so fingers crossed that it won't be five months before that one comes out. Eheh. Also thanks for keeping up with this if you like it! I genuinely do have a lot planned for this series, if I could only get past my own excitement for other ideas lol

Toriel’s phone rang. It was a relief to see Alphys’s name pop up on the caller ID. Frisk had let her know that the skeleton brothers weren’t coming in, something about poor Papyrus being too spooked to leave the house with Undyne missing. She understood, of course, it was a heartbreaking situation, but it was always better to hear from the parent directly.

“Hello, Alphys!” Tori replied cheerily, looking over her class on lunch break. The scientist sure knew the her sons’ usual schedule, it could have been difficult if she called during a lesson.

“O-ah, uhm, hi-hi Que- Toriel,” Alphys corrected herself, sounding frazzled on the other line. The teacher smiled patiently, waiting for her to explain that the boys wouldn’t be in. “I wa-was, hoping... Y’know, b-because Un-Undyne is... Well, she-she’s gone, that maybe you cou-could take the boys home wit-ith you after school. A sl-sleep over with Frisk, may-aybe? If that’s oka-kay? I want to- to go look for-”

“Alphys, of course I can come pick them up. Poor Papyrus... is he feeling better, then?” Toriel felt a bit hopeless. This mess is all so awful; she can’t imagine the strain on her little friends. The line went silent for a few moments after that.

“Tori... Are the-they not at school?”

\--

 

The officers quickly learned Sans and Papyrus were friendly little  _ menaces _ . The two had been separated, much to each of their concerns, because not a single question had been actually answered between the two of them. They were geniuses at getting the conversation off track. More than once Dupoir caught himself telling the little guys about his family or a recent hard case, instead of the  _ actual _ case at hand. So, Sans was handed off to a trusted investigator, Wallace- good ol’ Willy- and Papyrus stayed with Dupoir.

“oh, hey, it’s been a while.” Sans looked around the little interrogation room, more amused at the trouble they’ve been causing than worried. 

“Kid, I kinda hoped I’d never see ya’ again.” Wallace gave a sigh, rubbing at his eyes. It came out much harsher than he intended- he would much rather see no one but other policemen in his line of work, frankly.

“wow, rude,” Sans snickered, knowing exactly what he meant.

“No- I mean... You know, why don’t we make this quick? You give me the number for whoever’s watching out for you two these days, we’ll call them, and you can head on home.”

A few rooms back, Papyrus swung his feet, watching Dupoir sit down. He decided he liked the man after about an hour, which made him feel worse about making this so hard on him. Sans had a plan though- a real good plan.

“Think we can stay on task without Punsy in the room?” The man quirked a grin at the little boy, and Papyrus laughed.

“That’s a good name for him! You don’t even know how many puns he makes a day...” He gave a solemn shake of the head.

\--

“Alright-”

\--

“First Question-”

\--

“Where are your parents?” Each boy considered their question carefully. Well... Legally they don’t have parents...

\--

“Dead,” Sans responded coldly- and 100% seriously.

\--

“Sans told me they’re on vacation. I don’t know where they could have gone, though! That was back when we were underground, and there’s really a limited amount of places you can go underground. I checked all over...” Papyrus gave a sharp frown, emphasizing the tears in his eyes. “But, I have Sans!”

\--

Both men sighed. Fine.

“Uh huh...”

\--

“Okay,”

\--

“So... is there someone we can call to have you picked up? Someone that looks out for you?”

\--

“hmmm,” Sans gave it a long thought, “oh! what about uh,” He motioned for the man to write it down, and Wallace complied easily. Finally, someone to call pick the little ruffians up.

“8-6-7,” He paused, watching him write it down. “5-3... 0-9.” An exasperated sigh fell from the human and Sans grinned.

“... Sans.” 

“8675 3 0 niiiiiine,” Sans sang, swinging his feet and shifting in his seat. Wallace took a drink as Sans finished out his little song.

\--

“Oh, gee, Mr. Dupoir, I don’t have any phone numbers... Sans is the one who always remembers that stuff.” Papyrus actually didn’t know any phone numbers, that’s not a lie at all. He just answered the phone when it rang, Sans didn’t like talking on the phone.

The man gave a nod.

\--

“I know you don’t have enough money to buy clothes like that, so either you two are li’l thieves, or there’s someone else providin’-”

\--

“Where do you get such cool shoes like that? Surely you didn’t just find them, -”

\--

“Who’s taking care of you two, then?”

\--

“uhh, no one.” Sans shifted uncomfortably in his chair. It definitely came across as suspicious, and the cop frowned.

“Hey, kid, it’s alright... Are they hurtin’ you? ‘S that why you ran away?” He gestured down at the little backpack they sifted through when Sans and Papyrus arrived.

“wow, wow, no dude, nothin’ like that. this is just some monster generosity. a few of the shops hooked us up when we went to school.” The man lit up and Sans immediately knew he’d screwed up. School. Tori. That was definitely a number they could call, a number that was logged into their system for easy access.

“School, huh?” Wallace tapped his pen against the desk, smug expression on his face. It has been too long of playing in circles with these two to not take  _ some _ pride in getting an answer. “So you’re skipping, then?”

“... well, yeah. it’s tuesday.”

“What’s special about Tuesday?”

“it’s a weekend?” The boy’s brows knitted in confusion at the man. Almost genuine enough to pass. Almost.

“Ah, well, why don’t I just ring up the school to be sure...” Wallace stood, pushing his chair in behind him. “C’mon, you too, kid.” Sans tried to hide the guilt and horror in his expression, but it was impossible. He ducked down and picked up his bag, quick to follow the man out of the room. To keep up with Wallace, Sans had to trot, walking through the halls just behind him. The investigator paused part way and took his hand in a gentle, comfortable handhold, but not a friendly one. The kind of handhold he could technically pull out of, but also told him wandering off was against the rules. It was very... parent-like. The man paused again at his office to check in on Dupoir. They caught the tail end of a conversation about pasta recipes.

“Hey, got a lead on the kiddos, got the time to call?” He asked, clearly amused to see the older guy so animated. Sans shot his brother a little look, and Papyrus nodded.

“Sure, heh.” Dupoir turned to grab at his phone, and Wallace entered the room, letting Sans’s hand go under the assumption that he had nowhere to run.

On the contrary. Sans knew exactly where he was headed. It was time to put his plan into action. He slid his bag over to Papyrus and slipped out of sight from the door before sprinting down the hall. He knew he saw it on the way back to the office- in a little office labeled ‘Monster Unit Head Investigator’. Sans slipped into the room once he spotted it and used magic to lock the door behind him, then slid to the floor. Footsteps thundered outside the door, and even a high pitched voice called his name. Papyrus! Heh, the little booger was ‘helping’ them.

“Oh, man! I’m so sorry, sirs, he gets spooked sometimes...” The footsteps padded away after gentle encouragements that it was alright and that they would find his brother. Only then did Sans stand, going straight to the desk and sitting down in the overly plush chair. He gave it a quick spin for good luck before sifting through the files on the desk. It wasn’t hard to find her’s at all, it was pretty much on top. There was a number that appeared random to Sans, Undyne’s full name, and a few things paper clipped to it announcing it ‘still in progress’. He threw it open and began to sift. There... was so much more in it than he ever expected. Pictures- mainly somewhat blurry surveillance images.

One thing in particular stood out sharply. Police uniforms. Men in police uniforms had taken Undyne, it was right here in the pictures. Righteous anger burned in Sans, and he continued searching. The next thing that stood out was a large, old building. It didn’t look like anything special, other than the car that Undyne had been put into was parked in front of it. (He even compared license plates, just to be sure.) It took a while, but he thumbed through it all. Pictures, witness statements, leads, everything. Had they even looked into the building at all?! Or... Or had the policemen decided to get rid of Undyne. She had been a thorn in their side, after all, adamantly pushing monster rights and being very vocal and confident. Everyone believed in Undyne. She was monster kind’s hero in about as many ways as Frisk was.

Wait, was?! IS!! Sans was finding her. Now.

A bang at the door interrupted his thoughts, and his head shot up from where he had been reading. Behind the bulletproof glass he could see Dupoir staring at him in shock, Pap just at his feet. Wallace came into view, just before slamming his fist against the door again.

“KID! C’MON, YOU’RE NOT IN TROUBLE, JUST COME OUT.” The muffled voice was still very loud through the door, clearly irritated. Sans’s eye lit up blue. He knew exactly where to go, now. The address was right there in his hands.

“SANS! NO!” Papyrus screeched out, just before he teleported away. That wasn't the plan.

 

\--

  
Alphys’s phone rang. There was no relief behind the click of her picking up.

**Author's Note:**

> Thanks for reading!! <3 I super appreciate comments and kudos, lemme know if you liked it!
> 
> My tumblr is undertaletrashbin.tumblr.com my beta's is belzarvie.tumblr.com, check out the 'MSA' tag on my blog to see some art and different thing I post about this au for.


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